Process and specialized apparatus have been described in the prior art which have been specially adapted for the electrometric determination of the cyanide ion content of solutions thereof. Heretofore, it has not been possible, however, to apply this specialized apparatus to solutions containing cyanide ion, a strong reducing agent and a metal ion. This was due to the fact that the metal ion would be deposited on the electrode as the free metal and would eventually render the electrode inoperative. Applicant has provided a solution for this problem which is a novel method for measuring the cyanide ion content of metal ion containing solutions.